mean

[red and white kop!]

the price of a CD is denoted by $x. for 60 CDs bought in different stores it is found that sigma(x-12) = 53.40. Calculate the mean price of these CDs. The mean price of a further 40 CDs is found to be $11.64. Find the mean price of the 100 CDs.

The first problem was easy, divide 53.40 by 60 and add 12. BUt with the second one i don't know what method to use i know it must be more complicated than adding the two means and dividing by two

 

[Deleted member 4993]

the price of a CD is denoted by $x. for 60 CDs bought in different stores it is found that sigma(x-12) = 53.40. Calculate the mean price of these CDs. The mean price of a further 40 CDs is found to be $11.64. Find the mean price of the 100 CDs.

The first problem was easy, divide 53.40 by 60 and add 12. BUt with the second one i don't know what method to use i know it must be more complicated than adding the two means and dividing by two

\(\displaystyle \mu \ \ = \ \ \frac{cost \ \ of \ \ 100 \ \ CDs}{100} \ \ = \ \ \frac{60\cdot {\mu}_1 \ \ + \ \ 40 \cdot 11.64}{100}\)